Completing and signing Form I-864 makes you the sponsor. Please note: Students also may be required to complete a Residency Affidavit.To start the declaration, the person should state their complete name and address, as well as their country of citizenship. An I130 affidavit is a written statement from friends, family members, or associates who can attest to the genuine nature of your marriage. 1. Talk to the person immigrating to the US. The person for whom you write an affidavit should be someone you know very well. The sponsor is usually the petitioner who filed an immigrant petition on behalf of the intending immigrant. I saw the one on this site but it's so confusing. An affidavit is basically a sworn letter.